The globalization of the tobacco epidemic poses significant morbidity and mortality burdens, with the brunt of impact increasingly borne by low-middle income countries. Research partnerships between investigators from high-income countries with well developed tobacco control research programs and their counterparts in low-middle income countries are needed to effectively address this global public health crisis. The Dominican Republic (DR) is a key site that mirrors the trends in Latin America: it is a low-middle income tobacco growing country with significant tobacco use and high levels of secondhand smoke exposure, and it is at a very early stage of tobacco control. The proposed project will assess baseline knowledge, attitudes, exposures, and behaviors regarding tobacco use and secondhand smoke, provide a randomized controlled trial of community-partnered interventions around secondhand smoke and tobacco cessation, and develop and implement a dissemination plan for national and regional impact and translation of methods and results to other underserved groups as appropriate. A multimethod assessment approach will be used, to include qualitative community assessments (RAPs), a series of quantitative surveys (household surveillances, community and smoker cohort surveys, and health care provider surveys), and a biomarker assessment of secondhand smoke exposure. Eight economically disadvantaged communities will be randomized to intervention or control conditions in a lagged treatment design; interventions will be developed and implemented based on the evidence base from other countries and from a current DR trial, and on input from national and local DR workgroups using a community partnered approach. The intervention is hypothesized to decrease tobacco use rates, increase the number of smokefree homes, denormalize smoking, increase awareness of and change attitudes regarding tobacco use and secondhand smoke risks, decrease exposure to secondhand smoke, and increase health care provider intervention in intervention- relative to control communities, with differences by geographic and demographic characteristics to be examined. The project will also engage international, national, and local DR workgroups to maintain communication of findings to key partners, host a national DR tobacco control conference with regional representation, and develop other action steps for local and regional dissemination of findings and evidence based interventions, resources, and infrastructures. Finally, the project will coordinate with the University of Rochester Clinical and Translational Sciences Institute for translation of current evidence based approaches and methodologies for implementation in the DR, and to explore whether any methodologies or interventions from the proposed trial in the DR can be translated to underserved groups in the United States. Effectively engaging early stage low-middle income countries in tobacco control research will be critical to reducing tobacco use and the burden of tobacco-caused illnesses globally.